LF Purge Pac

Long-Lasting Purged Packing Cases

Cook Compression LF Purge Pac® assemblies use patented* Low-Friction technology to effectively seal the purge or buffer medium while extending the service life of the packing cases.

The Cook Compression “AL” ring is known throughout the industry as state-of-the-art sealing technology for purging or buffering environmentally sensitive packing cases. Cook Compression LF Purge Pac assemblies build on this proven technology to take purge and buffer seal performance to the next level.

Developed by Cook Compression engineers, Low-Friction (LF) technology uses springs and pressure plates to effectively side-load standard seal rings without the increased heat generated by a wedge-type ring. The resulting lower rod temperatures enable purged and buffered packing cases to last longer.

*US Patent #8,251,372

LF Purge Pac assembly illustration

Reduced Rod Temperatures

Field data and internal testing demonstrate that LF technology reduces rod temperatures by 50°F (27.8°C) or more compared to the AL ring.

Simplified Installation, Maintenance

The convenient and innovative cartridge design of the LF Purge Pac assembly simplifies installation and maintenance by eliminating the need to handle small, loose parts.

Retrofit Capability

An LF Purge Pac assembly can be retrofit to most packing cases with at least 1.33 inch (33.78 mm) of axial space. If space is limited, the axial dimension can be reduced to 1.19 inch (30.23 mm) by substituting thinner seal rings.

LF Purge Pac assembly 3D model - exploded view


  • Extends seal ring and packing case life
  • Forms a virtually leak-proof chamber for purge or buffer medium
  • Retrofits to most packing cases
  • Accommodates standard size seal rings
  • Cartridge design for trouble-free field maintenance